Examples of electronically controlled cartridge control valves for fuel injectors are shown in U.S. Pat. No. 5,494,219 to Maley et al., U.S. Pat. No. 5,407,131 to Maley et al., U.S. Pat. No. 4,869,462 to Logie et al., and U.S. Pat. No. 4,717,118 to Potter. In each of these examples, the injector includes a mechanically actuated fuel pumping plunger and an electronically actuated fuel pressure control valve assembly. The pressure control valve assembly includes a solenoid operated poppet valve that controls fuel pressure in the injector in order to control fuel injection delivery. Fuel pressure is controllably enabled to be developed within the injector by electrical actuation of the pressure control valve assembly. Fuel pressure is controllably prevented from developing within the injector by not electrically actuating the pressure control valve so that fuel can spill through a return passage while the plunger is undergoing a portion of its pumping stroke.
In such electronically controlled fuel injectors, the armature of the pressure control valve assembly moves the poppet valve in one direction until it engages a valve seat, and holds the poppet valve in its closed position to enable fuel pressure to be developed in the injector, eventually resulting in fuel injection. At the end of the fuel injection cycle, the solenoid is de-energized, and a return spring moves the poppet valve member off the valve seat, returning the poppet valve member to its open position, which prevents the development of fuel pressure by spilling the fuel back to a fuel reservoir.
In these prior art control valves, the solenoid is of a dual pole design, which results in a relatively large armature that is pulled toward the solenoid coil when the same is energized. Depending upon the location of the valve seat within the control valve, space constraints can often limit the size of the coil and hence the amount of force that the solenoid can produce. This in turn limits the actuating speed of the valve and complicates the construction of the same, both by the difficulty of incorporating the solenoid within the valve body and by the increased number of components necessary to do the same. Reducing the total number of components in a valve can also often times decrease sensitivity to critical tolerances, that might otherwise be stacked in prior art designs. In addition to these problems, engineers are motivated to avoid problems associated with intersecting high pressure bores, which sometimes result in valve body cracking and/or leaking high pressure plugs.
The present invention is directed to overcoming one or more of the problems set forth above.